This invention relates to oxidation colorants containing a special combination of primary and secondary intermediates for coloring keratin fibers.
By virtue of their intensive colors and good fastness properties, so-called oxidation colorants play a prominent role in the coloring of keratin fibers, particularly human hair. Oxidation colorants contain oxidation dye precursors, so-called primary intermediates and secondary intermediates. The primary intermediates form the actual dyes with one another or by coupling with one or more secondary intermediates in the presence of oxidizing agents or atmospheric oxygen.
Good oxidation dye precursors are expected to satisfy above all the following requirements: they must form the required color tones with sufficient intensity and fastness during the oxidative coupling reaction. In addition, they must be readily absorbed onto the fibers with no significant differences--particularly in the case of human hair--between damaged and freshly regrown hair (levelling capacity). They must be resistant to light, heat and the effect of chemical reducing agents, for example permanent wave lotions. Finally, if they are used to color hair, they should not overly stain the scalp and, above all, should be toxicologically and dermatologically safe.
The primary intermediates normally used are primary aromatic amines containing another free or substituted hydroxy or amino group in the para position or the ortho position, diaminopyridine derivatives, heterocyclic hydrazones, 4-aminopyrazolone derivatives and 2,4,5,6-tetraaminopyrimidine and derivatives thereof.
Special representatives are, for example, p-toluylenediamine, 2,4,5,6-tetraaminopyrimidine, p-aminophenol, N,N-bis-(2-hydroxyethyl)-p-phenylenediamine, 2-(2,5-diaminophenyl)-ethanol, 2-(2,5-diaminophenoxy)-ethanol, 1-phenyl-3-carboxyamido-4-amino-5-pyrazolone and 4-amino-3-methylphenol, 2-hydroxy4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diaminopyrimidine and 2,5,6-triaminohydroxypyrimidine.
The secondary intermediates used are generally m-phenylenediamine derivatives, naphthols, resorcinol and resorcinol derivatives, pyrazolones and m-aminophenols. Particularly suitable secondary intermediates are .alpha.-naphthol, pyrogallol, 1,5-, 2,7- and 1,7-dihydroxynaphthalene, 5-amino-2-methylphenol, m-aminophenol, resorcinol, resorcinol monomethyl ether, m-phenylenediamine, 1-phenyl-3-methyl-5-pyrazolone, 2,4-dichloro-3-amino-phenol, 1,3-bis-(2,4-diaminophenoxy)-propane, 2-chlororesorcinol, 2-chloro-6-methyl-3-aminophenol and 2-methyl resorcinol
By combination with various secondary intermediates, a certain primary intermediate can form a broad range of color tones. Nevertheless, it is often not possible to obtain the large range of natural color tones with a single primary intermediate. In practice, therefore, a combination of various primary intermediates and secondary intermediates has to be used to obtain a single natural-looking color. Accordingly, there is a constant need for new improved secondary intermediate/primary intermediate combinations. This applies in particular to the blues where conventional dyes are often not entirely satisfactory in their level-dyeing capacity and their resistance to cold waving and washing.
Accordingly, the problem addressed by the present invention was to provide new primary intermediate/secondary intermediate combinations in the blue range which would satisfy the requirements oxidation dye precursors are expected to meet to a particular degree.
It has now surprisingly been found that a special combination of a known secondary intermediate and a known primary intermediate leads to dark blue colors of high brilliance which are additionally distinguished by high fastness to rubbing.